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Methane Oxidising Bacteria as Environmental Indicators

This report focuses on methane oxidising bacteria (methanotrophs). The key function of methanotrophs as methane consumers and degraders of halogenated hydrocarbons bring them in the perspective of being useful indicators of environmental perturbations. Effects of climate on diversity and temperature adaptation as well as the capacity of different methanotrophs to degrade two atmospheric pollutants (chlorofluoromethanes) was investigated. None of the methanotrophs were found to be adapted for growth at permanently low temperatures although type I methanotrophs grew better at lower temperatures than the type II methanotrophs. Some of the methanotrophs were able to degrade dichlorofluoromethane while chlorodifluoromethane degradation was not demonstrated. No correlation was found between the degradation capacity and the origin of the isolates (landfill or wetland soil), or characteristics of their methane monooxygenase enzymes. The project did not identify a simple correlation between climatic variation or environmental stress and the variation in composition of the methanotroph community. More knowledge about temperature dependent interactions between type I and type II methanotrophs is needed before the composition of methanotrophs can be implemented as an indicator revealing ecological consequences of e.g. changes in climate.

Methanotroph communities in Nordic high organic soils

The application of the new SSMS method to soil samples from a wetland near Roskilde and from Skellingsted landfill, Denmark, resulted in successful isolation of several methanotrophs. Skellingsted represents a comprehensively studied landfill with regard to methane oxidation (Kjeldsen & Fisher 1995, Christophersen et al. 2000, Scheutz & Kjeldsen 2003). Different methanotrophs were isolated from these sites and variation in the cell types is illustrated in Fig. 7.